There are over 1,700 exchange traded products trading in the U.S. Just over 40 have lost 30 percent or more year-to-date, but underscoring weakness in natural gas futures and equities, several of this year's worst-performing ETFs are natural gas funds.

That dubious group includes the First Trust ISE-Revere Natural Gas Index Fund (NYSE: FCG). FCG tracks the ISE-REVERE Natural Gas Index, an equal-weighted index comprised of exchange-listed companies that derive a substantial portion of their revenues from the exploration and production of natural gas, according to First Trust.

As can be gleaned from the United States Natural Gas Fund (NYSE: UNG)'s nearly 38 percent slide over the past year, exploring for and producing natural gas has not been the most profitable of endeavors. The U.S. is awash in natural gas. Last week, the U.S. Energy Information Administration said U.S. natural gas inventories climbed to 52 Bcf (billion cubic feet) to 2,880 Bcf for the week ending July 24, 2015.

While demand for natural gas is not terrible (shipments to power plants climbed 14 percent last week on a year-over-year basis), there is simply too much supply to make production profitable for even some large-cap producers, let alone some of the mid- and small-caps found among the 30 stocks in FCG's lineup. The median market value of FCG's holdings is $2.9 billion.

To be precise, FCG is down 43.3 percent year-to-date. The ETF closed at $6.36 Wednesday, a price range at which ETF issuer will consider reverse splits, though it should be noted that First Trust has not made any public comments to that effect.

Quantifying FCG's woes at the individual stock level is not difficult. There are 23 S&P 500 members down 30 percent or more this year. Three members – Chesapeake Energy (NYSE: CHK), Range Resources (NYSE: RRC) and Southwestern Energy (NYSE: SWN) – are FCG holdings. Those stocks combine for 11.5 percent of the ETF's weight.

FCG has a triple-leveraged equivalent, the Direxion Daily Natural Gas Related Bull 3X Shares (NYSE: GASL). With a year-to-date loss of 86.4 percent, GASL is one of the worst-performing ETFs, leveraged or otherwise, and trading below $6 is another candidate for a reverse split.

What is interesting is that natural gas's struggles are not chasing investors from the corresponding ETFs. Year-to-date, investors have added $36.1 million to FCG and $7.2 million to UNG. GASL trumps both with 2015 inflows of nearly $89 million.